The invention relates to combustion apparatus, and more particularly to a sealing arrangement preventing leakage of combustion products through penetrations and interfaces, such as piping and mixer and burner penetrations and end wall interfaces, without requiring leak-tight seals.
In a forced draft combustion system, the pressure of gases within the combustion chamber is usually greater than that of the surroundings. It is often difficult to assure that penetrations for components that pass through the wall of the combustion chamber will not leak, especially since such components must often be readily removable for service or replacement. Also, it is usually necessary for a wall or panel of the combustion chamber to be removable for inspection or maintenance of the combustion chamber or heat exchanger within it. While it is possible to provide individual leak-tight seals for such components, it is expensive to do so, and furthermore it cannot be assured that they will be maintained in proper condition.
The present invention provides penetration and interface seals that are permitted to leak slightly. The invention conditions the environment of the seals so that the leakage is not detrimental. The invention provides an air seal arrangement and combination including a buffer space at penetrations and interfaces, and pressurizes the buffer space to a higher pressure than the combustion chamber, such that any leakage flows into the combustion chamber rather out of the combustion chamber. The direction of leakage into the combustion chamber prevents unwanted escape of combustion gases. Any leakage from the buffer space to the atmosphere will simply be air leakage. The arrangement prevents leakage of gases from the combustion chamber without relying upon leak-tight fittings or seals.